Method of blowing, filling and capping containers

Abstract

The invention concerns a method of blowing and filling a container (120) from a preform, the method comprising: —placing a preform within a mold (140), —stretching the preform —injecting a liquid into the preform after the stretching has started so as to cause expansion of the preform within the mold, thereby obtaining a blown and filled container (120), —capping the blown and filled container (120).

Claims

1. A method of blowing and filling a container from preform, the method comprising: placing a preform within a mold; stretching the preform; injecting a liquid into the preform after stretching has started so as to cause expansion of the preform within the mold, thereby obtaining a blown and filled container; capping the blown and filled container; and the capping is performed within a predetermined period of time after obtaining the blown and filled container so as to increase pressure inside the capped container to between 0.3 and 1.5 bar above atmospheric pressure resulting from shrinking of the capped container.

2. The method of claim 1, wherein capping is performed between 1 second and 2 minutes after obtaining the blown and filled container.

3. The method of claim 2, wherein capping is preformed between 1 second and 30 seconds after obtaining the blown and filled container.

4. A method of blowing and filling a container from preform, the method comprising: placing a preform within a mold; stretching the preform; injecting a liquid into the preform after stretching has started so as to cause expansion of the preform within the mold, thereby obtaining a blown and filled container; capping the blown and filled container within a predetermined period of time after obtaining the blown and filled container; and shrinking the capped container so as to increase pressure inside the capped container to between 0.3 and 1.5 bar above atmospheric pressure.

5. The method of claim 4, wherein capping is performed between 1 second and 2 minutes after obtaining the blown and filled container.

6. The method of claim 4, wherein capping is performed between 1 second and 30 seconds after obtaining the blown and filled container.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying figures in which:

(2) FIG. 1 is a schematic view of an apparatus for simultaneously blowing and filling containers according to an embodiment of the invention;

(3) FIG. 2 is a schematic enlarged partial view of the injection head and mould represented in FIG. 1;

(4) FIG. 3A represents a blown and liquid-field container 22 within mould 12;

(5) FIG. 3B represents container 22 out of its mould;

(6) FIG. 3C represents container 22 at a capping station;

(7) FIG. 3D is a partial view of supporting means for supporting container 22 at the capping station;

(8) FIG. 4 illustrates the resistance to top load of three different bottles of water;

(9) FIG. 5 is a schematic and overall view of an apparatus according to another embodiment of the invention;

(10) FIGS. 6A-D are successive schematic views illustrating the different operations for bringing and positioning a cap on the capping head and fixing it on the dispensing opening of the container.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(11) FIG. 1 schematically represents an apparatus 10 in which is implemented a method for simultaneously blowing and filling containers, such as bottles, from preforms according to an embodiment of the invention. It is to be noted that the invention is not limited to such an apparatus.

(12) These preforms may be made of thermoplastic polymer.

(13) Apparatus 10 comprises a blowing mould 12 for enclosing a preform. Such a preform is first manufactured through a moulding process and then heated before being positioned within mould 12 as disclosed in Applicant's patent EP 1 529 620 B1.

(14) The preform usually assumes the shape of a cylindrical tube closed at its bottom end and open at its opposite end.

(15) Mould 12 is for example a two-part mould of which the two parts or side halves 12a, 12b define an inner cavity 14 when assembled together.

(16) Firstly, the two side halves are spaced apart from each other under the action of moving means (not represented in the drawing) for inserting a preform 16 therebetween.

(17) The moving means may be piston devices for example.

(18) Next the two side halves 12a and 12b are moved back toward each other so as to come into contact along a joint plane.

(19) As represented in FIG. 1, preform 16 is inserted into cavity 14 before the beginning of a blowing and filling method according to the invention.

(20) Once the preform has been positioned within mould 12 only the open end of the preform is visible from above the mould.

(21) The shape of the cavity corresponds to the shape of the achieved container and it will be wholly occupied by the formed container at the end of the blowing and filling method.

(22) It is to be noted that mould 12 may alternatively be composed of more than two parts depending on the manufacturing process.

(23) For instance, a third part (base or bottom part) may be added at the bottom of the mould so as to define at least a part of the inner cavity bottom.

(24) Apparatus 10 further comprises a liquid injection circuit 18 and injection means for injecting a liquid into preform 16.

(25) Injection means comprise an injection head 20 which comes into a sealing contact (for liquid tightness purpose) with mould 12 and preform 16.

(26) FIG. 2 is a schematic enlarged partial view of injection head 20 disposed above mould 12.

(27) Mould 12 encloses a blown and filled container 22 (here, for example, a bottle filled with water) that has been obtained from preform 16 through the blowing and filling method that will be described subsequently.

(28) The injection head comprises an injection valve device 24 that includes an injection nozzle 28 mounted within an inner housing 26.

(29) Injection head 20 is substantially cylindrical in shape as partially illustrated in FIG. 2 and inner housing 26 is also cylindrical in shape and both are coaxial.

(30) Injection valve device 24, and more particularly injection nozzle 28, is movable along a longitudinal axis A between an injection position (open position) allowing liquid to be injected into the preform and a rest position (closed position) in which the injection nozzle 28 rests against an inner surface 26a of the injection head in a sealing engagement so as to prevent any flow of liquid from the injection head into the preform.

(31) Longitudinal axis A is here the vertical axis along which injection head 20 and mould 12 are substantially aligned.

(32) Axis A is a symmetry axis to container 22 as well as to preform 16.

(33) As represented in FIG. 2, injection nozzle 28 is in the closed position (lower position) which is occupied when the container has been blown and filled at the end of the manufacturing method.

(34) In the open position injection nozzle 28 is in an upper position at a distance from the inner surface 26a. This upper position is not represented in the drawing for the sake of clarity but it is located above a transverse channel 30 (represented in dotted lines) that is provided in a peripheral wall 32 of injection head 20.

(35) This feed channel is connected to liquid injection circuit 18.

(36) Moving the injection nozzle 28 away from inner surface 26a and above channel 30 makes it possible for the liquid that is in the circuit 18 to flow from channel 30 to the preform (in FIG. 2 the preform 16 of FIG. 1 is replaced with the formed container 22).

(37) Apparatus 10 also comprises stretching means 38 for stretching preform 16 when enclosed within mould 12.

(38) Stretching means comprise a stretch rod 38 which is in a sliding connection with the injection nozzle 28 as partially represented in FIG. 2.

(39) For example, stretch rod 38 is in alignment with axis A and traverse injection nozzle 28 in a fluid-tight manner.

(40) The stretch rod 38 of FIG. 1 embodiment is actuated upon command to be inserted downwardly into preform 16 so as to stretch the latter while a filling liquid is injected thereinto with a view to causing expansion of said preform within the mould.

(41) Actuating means for actuating stretch rod 38 have not been represented for the sake of clarity.

(42) In FIG. 2 stretch rod 38 is in a retracted position after being used.

(43) Apparatus 10 comprises a valve device 40 that enables flowing of liquid through circuit 18 when opened and prevents liquid from flowing through the valve device and downstream thereof when closed.

(44) Valve device 40 is actuated upon command.

(45) Liquid to be injected into the preform, e.g. water, is supplied from a source of liquid S which feeds said liquid to a pump device 42 of system 10.

(46) Pump device 42 is located upstream of valve device 40.

(47) Such a pump device is suitable for delivering a constant pressure, e.g. between 3 and 7 bars.

(48) Pump device 42 is suitable for providing a predetermined volume of liquid and pushing it through liquid injection circuit 18.

(49) As further represented in FIG. 1, a flow valve 44 is mounted in parallel of pump device 42 as a safety valve.

(50) This valve acts as a discharge valve in order to protect the pump device, for instance when the liquid pressure is building up or if there is no container being manufactured.

(51) Apparatus 10 comprises a duct 46 that is connected to pump device 42 at one end and to injection head 20 at the opposite end. Valve device 40 is mounted onto duct 46. It is to be noted that duct 46 is part of liquid injection circuit 18.

(52) Apparatus 10 also comprises temperature controlling means 48 for controlling the temperature of mould 12 in the course of performance of the method. Means 48 may be part of a processing device 50 (e.g. a computer) or distinct thereform. Processing device 50 performs the execution of the different steps or operations of the method and, for example, controls the actuation of the different elements of the apparatus (pump device, valves, stretch rod, etc . . . ).

(53) In the course of performance of the blowing and filling method according to an embodiment of the invention, the stretch rod 38 is actuated during a stretching phase whereas valve device 40 is in a closed position, thereby preventing liquid from being injected into preform 16.

(54) Stretch rod 38 is downwardly engaged into the open end of the preform 16 so as to come into contact with the closed bottom end thereof. The stretch rod is then further actuated to push the closed end downwardly and stretch the preform accordingly in a controlled manner.

(55) After a predetermined period of time has elapsed following the start of the stretching phase, the injection phase starts for injecting the liquid into the preform both for forming the container and filling it.

(56) The temperature of the mould is less strictly controlled than in the prior art since shrinkage of the container is allowed to some extent. By way of example, in a conventional process, approximately 4,500 kJ need to be evacuated per mould and per hour.

(57) The invention makes it possible to reduce this value.

(58) The injection phase starts with the opening of valve device 40 and operation of pump device 42. Actuation of valve device 40 is controlled through processing means 50.

(59) Also injection nozzle 28 is actuated to be raised in its upper position (open position) under the control of processing means 50.

(60) Pump device 42 is operated in a controlled manner so that liquid is pushed or displaced through liquid injection circuit 18 and injection head 20 to preform 16 (for being injected thereinto) in accordance with a predetermined injection or filling curve. Liquid is injected into preform 16 while the preform is being stretched so as to cause expansion of said preform within mould 12. EP 1 529 620 B1 provides further details on an embodiment of a blowing and filling method.

(61) In FIG. 2 only the upper part of a blown and liquid-filled container has been represented at the end of the injection phase.

(62) As illustrated, the open end of the preform has been shaped into a dispensing opening 52 that protrudes from above the mould.

(63) Opening 52 has a neck 54 with an outside thread and a flange or neck ring 56 that is provided at the basis of the neck.

(64) In particular, neck ring 56 rests against a shoulder 58 provided at the upper part of the mould around the container 22.

(65) The blown and filled container 22 assumes the complementary shape to that of the inner walls of the mould illustrated in FIG. 1.

(66) The blown and liquid-filled container 22 has been wholly represented in FIG. 3A inside mould 12.

(67) The method further comprises a step of opening the mould by moving the two mould side halves 12a and 12b away from each other so as to release container 22 from the mould.

(68) Container 22 is next handled by known handling means (not represented in the drawings for the sake of clarity) for being extracted from the mould and moved therefrom.

(69) FIG. 3B illustrates container 22 out of mould 12.

(70) Container 22 is transported to a next station 60 of the apparatus as partially represented in FIG. 3C.

(71) Station 60 comprises a capping head 62 which has holding means 64 for holding a cap 66.

(72) Cap 66 is intended to be fixed onto neck 54 of container 22.

(73) As represented in FIG. 3C, container 22 is brought into a position located below capping head 62 so that cap 66 is precisely above dispensing opening 52.

(74) Supporting means 68 are provided and arranged around the neck of the container so as to firmly maintain the container in a fixed position during the capping operation.

(75) More particularly, supporting means 68 are engaged with neck ring 56 under the latter.

(76) For instance, supporting means 68 assume the shape of a rigid plate of which a half has been represented in FIG. 3D.

(77) A central aperture 68a, e.g. of circular shape, is provided in the plate.

(78) The inner dimensions of aperture 68a are adapted to those of neck ring 56.

(79) Several anti-rotating means 68b, 68c, 68d are provided on the inner periphery of the aperture. Such means or devices are, for example, spikes.

(80) Thus, once the container has been fixed in position thanks to supporting means 68, capping head 62 is commanded to be lowered and driven into rotation as illustrated by the rotating arrow. This rotational movement of capping head 62 causes cap 66 to be rotated around neck 54, thereby tightly screwing cap 66 around the neck of the container.

(81) Other capping techniques may alternatively be envisaged for capping container 22. For example, press-on cap type or ultrasonic sealing techniques may be used. In case of ultrasonic sealing, the neck and the cap may be made together using over-moulding techniques.

(82) This capping operation takes place approximately 30 s after the container has been blown and filled with liquid.

(83) This quick capping operation enables building up a slight pressure inside the container. The thus capped container has therefore an increased mechanical strength and resistance to loading, in particular to top loading.

(84) A plurality of so reinforced containers may be positioned upon each other in layers.

(85) Thus assembled they form a stack that is resistant to loads applied from the top and the sides.

(86) Thanks to this mechanical reinforcement the containers may be piled up and transported on pallets while avoiding, or at least dramatically reducing, the risks for a pile or an assembly of containers to tilt or collapse.

(87) FIG. 4 shows three curves a, b, and c illustrating the mechanical resistance to top load of three different bottles filled with water.

(88) The graph represents for each curve the vertical force exerted on the bottle (expressed in kgf) as a function of the vertical deflection of the bottle (expressed in mm).

(89) Curve a has been obtained through a conventional blowing method applied to a preform weighing 18 g and having a length of 86 mm. The blown bottle has been capped several hours after having been blown.

(90) Curve b has been obtained through a stretch-blow moulding and filling method applied to the same preform as for a curve a.

(91) Curve c has been obtained through a stretch-blow moulding and filling method applied to a preform weighing 14.5 g and having a length of 78 mm.

(92) The bottle corresponding to curve c has been capped in accordance with the invention whereas, i.e. rapidly, the bottle corresponding to curve b has been capped much later, e.g. several hours after the obtaining (forming and filling) of the bottle.

(93) The comparison between curves a and b shows that the performance in terms of resistance to top load are similar for the same weight but with different manufacturing processes.

(94) Curve c shows that when capping the bottle takes place rapidly after the filling the performance of the bottle in terms of resistance to top load is increased. This is because an increase in pressure has been formed within the upper part of the capped bottle.

(95) For instance, the bottle of curve c undergoes a deflection of 5 mm under an external vertical force of almost 35 kgf whereas the same deflection is obtained with the bottles of curves a and b for a force less than 30 kgf.

(96) Also, this performance is obtained for the bottle of curve c with a lighter bottle since it has been manufactured with approximately 4 g of PET missing.

(97) Thus thanks to the invention lightweight containers with an increased resistance to top load may be manufactured.

(98) FIG. 5 illustrates a schematic and partial view of the main components of an apparatus 100 for simultaneously blowing and filling a plastic container from a preform according to another embodiment of the invention. This embodiment makes it possible to implement the method according to the invention which enables capping of the blown and filled container within a short period of time.

(99) For example, the container may be capped within 2 seconds after being blown and filled.

(100) As represented in FIG. 5, the container is a bottle 120 which has been filled with a liquid.

(101) Apparatus 100 comprises a mould 140 enclosing bottle 120 in the position of FIG. 5.

(102) Also, apparatus 100 comprises an injection head 160 through which the liquid has been injected into the bottle during its shaping.

(103) Apparatus 100 also comprises stretching means which, here, comprise a stretch rod as represented in FIGS. 1 and 2.

(104) Apparatus 100 further comprises a capping head 180 that is rotatably mounted relative to injection head 160.

(105) As represented in dotted lines, capping head 180 has a traversing hole 200 that is centered about a longitudinal axis A.

(106) Axis A is an axis of alignment along which injection head 160 and mould 140 are aligned in the manufacturing configuration of FIG. 5.

(107) Traversing hole 200 has two opposite sides 200a and 200b. Side 200a faces injection head 160 while opposite side 200b faces mould 140 and, more particularly, the dispensing opening 220 of container 120.

(108) Although not represented in the drawings, injection head 160 has an inlet (as inlet channel 30 in FIG. 2) through which liquid flows before entering into traversing hole 200 and dispensing opening 220 when capping head 180 rests against mould 140 and traversing hole 200 surrounds dispensing opening 220.

(109) This position is not illustrated in the drawings and represents the position in which the container is simultaneously blown and filled.

(110) Furthermore, apparatus 100 comprises driving means 240 for driving capping head 180 in rotation around an axis of rotation that coincides with longitudinal axis of alignment A.

(111) As represented in FIG. 5, driving means 240 are laterally offset relative to axis A and are coupled to the periphery of capping head 180.

(112) More particularly, driving means comprise a gear 260 which cooperates with a gear 280 provided at the periphery of capping head 180.

(113) These gears may be in a mesh engagement and, for instance, may be toothed gears.

(114) Gear 260 is for instance mounted on the output shaft 300 of a motor 240.

(115) Motor 240 is for example a brushless motor.

(116) This motor makes it possible to accurately control the force transmitted to capping head 180 and therefore to the cap during the screwing process that will be described subsequently.

(117) FIG. 5 shows a manufactured container 120 (bottle) after it has been simultaneously blown and filled (e.g. water) with a liquid through a conventional method such as described in the Applicant's patent application EP 1 529 620 and reminded of in the description made with reference to FIGS. 1 to 3A-D.

(118) Once the container has been blown and filled according to the above-described method, a cap has to be fixed to the dispensing opening 220 of the container.

(119) In this respect, injection head 160 and capping head 180 which are mobile together in a translational movement along axis A are caused to be raised along axis A so as to leave free sufficient space between capping head 180 and dispensing opening 220.

(120) It is to be noted that the connection between injection head 160 and capping head 180 is a rotatable connection comprising needle bearings.

(121) Such a rotatable connection is known to the skilled person.

(122) It is to be noted that dispensing opening 220 has a neck 320 with an outside thread 340 and a flange 360 that is provided at the basis of the neck. Flange 360 is positioned within a recess provided in the upper part of mould 140.

(123) FIGS. 6A to 6D illustrate successive views showing the capping process of the container.

(124) FIG. 6A is a schematic and simplified view representing container 120 maintained within mould 140 and capping head 180 away from mould 140 and neck 320. Injection head 160 has not been represented for the sake of clarity.

(125) Apparatus 100 comprises bringing means 380 for bringing a cap 400 to be fixed on dispensing opening 220. Bringing means 380 have been moved from a rest position (not represented) to an active position located between capping head 18 and dispensing opening 220.

(126) Bringing means 380 may assume the shape of a cap distributing plate provided, for instance, with a slight recess on the upper surface thereof for positioning and maintaining in a fixed position cap 400 on the plate.

(127) This plate may be a rotating plate comprising several caps at its periphery or an elongated plate which carries only one cap at one end and is elongated along an axis that is perpendicular to axis A.

(128) Thus cap 400 has been brought between capping head 180 and neck 320 and positioned below traversing hole 200 vis-à-vis side 20b thereof. Injection head 160 and attached capping head 180 are actuated to be lowered towards bringing means 380 and cap 400.

(129) As represented in FIG. 6B, capping head 180 is moved downwardly towards neck 320 and cap 400 is forcibly engaged within traversing hole 200 as capping head 180 is actuated downwardly.

(130) The inner dimensions of the traversing hole 200 (inner diameter) and the outer dimensions of cap 400 (outside diameter) are adjusted so that cap 400 can be introduced in force within traversing hole 200 and remain in place as represented in FIG. 6C.

(131) It is to be noted that cap 400 is partly engaged within hole 200.

(132) Cap 400 is kept in position within receiving means of capping head (inner whole of traversing hole 200) thanks to friction forces. Cap 400 is tight fitted within filled said receiving means.

(133) The degree of introduction of cap 400 into traversing hole 200 depends on the respective dimensions of the cap and the hole. The more the respective dimensions correspond to each other, the less cap 400 is introduced into traversing hole 200.

(134) In the present embodiment, cap 400 has been positioned within the receiving means of the capping head 180 only by virtue of the translational movement of the injection head and capping head.

(135) This is a very convenient means for rapidly putting in place the cap within the capping head which does not require any other device. Moreover, bringing means 380 may be simplified since they do not need to be movable along vertical axis A.

(136) However, other positioning means may be envisaged for positioning the cap within the receiving means of capping head 180.

(137) Other bringing means for bringing cap 400 between capping head 180 and the dispensing opening of the container may be alternatively envisaged.

(138) Reverting to FIG. 6C, once cap 400 has been appropriately positioned within traversing hole 200 bringing means 380 are withdrawn as indicated by the arrow.

(139) Next, capping head 180 equipped with cap 400 is driven into a downwardly translational movement along axis A thanks to the accordingly actuated injection head 160 so as to place cap 400 around neck 320.

(140) As represented in FIG. 6D, driving means 240 are activated in order to drive into rotation capping head 180 such as already described above.

(141) Capping head is therefore driven into rotation around axis A. This rotational movement of capping head 180 causes cap 400 to be driven into rotation around neck 320, thereby tightly screwing cap 400 around the neck of the container.

(142) Other capping techniques may be alternatively envisaged for capping container 120. For instance, press-on cap type or ultrasonic sealing techniques may be used. In case of ultrasonic sealing, the neck and the cap may be made together using over-moulding techniques.

(143) It will be appreciated that the apparatus which has been described is of a particularly simple construction and has movable parts or components which are capable of moving only according to fewer and simple movements (translation and rotation).

(144) Also, the capping head is either driven into a translational movement along longitudinal axis A (for example vertical axis) during the blowing, filling and capping process or driven into rotation during the last step of the capping process (FIG. 6D).